310钢蠕变裂纹扩展的温度和应力依赖性

本文在600～800℃和11.8～56.8MPa的初始净截面应力下研究了310钢蠕变裂纹扩展行为。试验结果表明，裂纹扩展激活能随裂纹长度增加而养活是由于断裂方式由沿晶向穿晶转变所致；第二阶段加载点位移速率具有蠕变速率特性，它表征裂纹前沿局部蠕变速率；初始净截面应为与Larson-Miller参数之间存在类似于蠕变试验中应力与Larson-Miller参数之间的关系。

DEPENDENCE OF CREEP CRACK GROWTH ON TEMPERATURE AND STRESS IN 310 STEEL

Subs critical crack growth behavior in 310 steel was studied under creep condition at the temperature of 600～800℃ and the initial not section stresses of 11.8～56.8MPa. The crack length was measured by a D.C. electrical potential drop technique in CT-specimens. The fracture surfaces were observed by scanning microscope. The results show that the apparent activation energy of crack growth decreases and the fracture mode changes from intergranular to intragranular with the increase of crack length. The secondary load point displacement rate has the characteristics of minimum creep rate and can represent the local creep rate in front of crack tip. The relation of the initial net section stress with Larson-Miller parameter is similar to that of stress with Larson-Miller para meter in creep test.